In general, a driver in a normal state may unconsciously show a variety of reflex responses such as righting reflex to match his or her head to the orientation of his or her body in preparation for a tilt of the body and tilting reactions to respond not to falling when he or she loses his or her balance.
However, if the driver is in an impaired state or is tired due to drinking, drug-taking, or the like, since exercise reflex capacity is greatly reduced as compared with the normal state although he or she opens his or her eyes, he or she may perform simple driving of following lanes. However, if a preceding vehicle is stopped suddenly or if a vehicle of a next lane cuts in suddenly, the driver may fail to suitably cope with it to cause a traffic accident.
Conventional technologies for determining a state of a driver are mainly technologies for determining his or her drowsy driving. The technologies for determining the drowsy driving of the driver may detect his or her eyes from an image captured by a camera and may determine his or her drowsy driving based on a change in a shape of each of the eyes, or may detect his or her mouth from an image captured by the camera and may determine his or her drowsy driving based on a change in a shape of the mouth.
Such conventional technologies for determining the state of the driver may be based on a change in a shape of a feature point in his or her face, generated due to sleepiness, and may fail to detect an impaired driver who has no change (e.g., an eye closing phenomenon) in a shape of each of eyes or has no change in a shape (e.g., a yawn) of a mouth.